Patent document SE 146 598 discloses a compressible unit, but the compression of the stacked separating discs is effected, after an insert has been moved down in the rotor body, by an expensive compression tool in a labour-intensive process.
U.S. Pat. No. 5,637,217 and WO 2004/020105 refer to examples of centrifugal separators provided with inserts of separating discs in the form of units which are held together and compressed by a plurality of rods or bolts through the disc set, thereby disturbing the flow through the disc set and hence the separation results. A large number of parts also have to be handled during assembly and disassembly, which are therefore labour-intensive operations.